Chronic release of hazardous substances began in the early 1900s.
Castro Cove is a shallow, protected embayment of San Pablo Bay (the northern portion of the greater San Francisco Bay estuary). The cove is near the Chevron Refinery in Richmond, Contra Costa County, California. At mean lower low water most of Castro Cove is exposed mudflat with areas of intertidal salt marsh. Castro Cove is bordered to the east by Wildcat Marsh, a large salt marsh, and to the west by the Contra Costa County Sanitary Landfill. The Chevron property forms most of the southern and western site boundary. Castro Creek and Wildcat Creek enter the cove on the east and empty into a 30 – 75 foot-wide channel that transects a portion of the cove. Castro Cove is not accessible to the public because it lies within the Chevron refinery property and is generally not navigable.
Restoration Implementation Phase.
Sediments in Castro Cove were contaminated by historical discharges of wastewater and storm water runoff from the Chevron refinery and other sources. Between 1902 and 1987, Chevron and its predecessors discharged refinery wastewater into Castro Cove. Although Chevron relocated the refinery's wastewater outfall in 1987 to offshore in San Pablo Bay, high levels of polycyclic aromatic hydrocarbons (PAHs) and mercury remained in sediments, with the highest concentrations found in the southern portion of Castro Cove near the old wastewater outfall.
Natural resources potentially injured include benthic invertebrates, fish, mammals, and birds. Federally listed endangered and threatened species that use Castro Cove include the salt marsh harvest mouse, clapper rail, and steelhead.
While the California Regional Water Quality Control Board (Water Board) worked on site cleanup requirements, NOAA and our natural resource co-trustees initiated a natural resource damage assessment (NRDA). The goal of the NRDA is to determine the type and amount of restoration required to restore injured natural resources. Chevron agreed to work with the trustees in a cooperative and expedited NRDA process. Our injury assessment and restoration activities pages provide more information. The trustees released a draft Damage Assessment and Restoration Plan / Environmental Assessment (DARP/EA) for public comment in November 2008, considered and incorporated public comments, and the final DARP/EA was released in June 2010.The trustees are currently implementing this final restoration plan.
Historical Clean Up Activities
The investigation and clean-up of Castro Cove was under the jurisdiction of the Water Board; it is not a federally listed Superfund site. In 1998, the Water Board requested that Chevron prepare a Sediment Characterization Work Plan under the Bay Protection and Toxic Cleanup Program. Several field investigation studies were conducted between 1999 and 2001. Based on the results of these studies and the results of benthic toxicity tests, approximately 20-acres of the intertidal mudflat in Castro Cove were identified as the Area of Concern (AOC). Total PAHs were measured at concentrations as high as 507 mg/kg, and mercury as high as 13 mg/kg. A Corrective Action Plan (CAP) for sediment remediation in the AOC was submitted to the Water Board in 2002 and revised and resubmitted in 2006. The Water Board prepared a California Environmental Quality Act (CEQA) Mitigated Negative Declaration, adopted the Corrective Action Plan, and issued a cleanup order to Chevron in November 2006.
The cleanup was completed in 2012 and resulted in the following:
Removal of 97,000 cubic yards of contaminated sediment over the 20-acre contamination hot spot. The removal activities were completely enclosed by a sheet pile wall to prevent discharge of contaminants during dredging.
Capping of 1.5 acres of wetland and 18.5 acres of mudflats on the former hot spot by beneficially reusing 50,000 cubic yards of clean dredged sediment from adjacent yacht harbors, and placing it over 45,000 cubic yards of clean Bay sand.
The 97,000 cubic yards of dredged contaminated sediments were hydraulically pumped into an inactive treatment pond located on the Chevron Richmond Refinery property. After dewatering, the sediments were mixed with soils and a stabilizing agent (e.g., cement or fly ash).